1. Field of the Invention
The present invention relates to a cold pilger rolling mill with a reciprocating roll stand, wherein the inertia forces of the mill stand can be balanced or compensated by counterweights which are arranged eccentrically on a crank drive which is connected to the roll stand through connecting rods.
2. Description of the Related Art
Federal Republic of Germany AS 18 15 521 discloses a pilger step-by-step-type rolling mill including a roll stand which is reciprocated in a horizontal plane. The connecting rods which drive the roll stand are pivoted to two crank means which are driven synchronously in opposition so as to provide an equalization of the inertia forces produced by the swinging masses of the roll stand in a plane extending through the axis of the material being rolled.
For a complete balancing of the inertia forces caused by the swinging masses of the roll stand in all planes extending through the axis of the material being rolled, the state of the art utilizes complementary weights which are fastened eccentrically on the two crank means, so that their projections onto the plane of movement of the roll stand shift at each moment of a complete operating cycle, opposite to the movement of the roll stand. In this way, a solution is offered for the problem inherent in the pilger step-by-step rolling process with reciprocating roll stand, namely that reciprocating parts which weigh many tons cause inertia forces which result in considerable mechanical problems.
For the desired complete balancing of the inertia forces, the previously known solution requires two connecting rods, which represent a considerable structural expense. Since the gears for the coupling of the shafts which are necessary for the balancing of the inertia force must transmit the entire power for the movement of the roll stand, two of each must be provided, so that the expense for bearings is also increased and a stable housing construction becomes very expensive. In addition, it is necessary to adapt to each other the two connecting cranks which are arranged parallel to each other in order to compensate deviations in the kinematic dimensions resulting from manufacture.